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529 lines
16 KiB
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529 lines
16 KiB
Plaintext
=======
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Widgets
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=======
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.. module:: django.forms.widgets
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:synopsis: Django's built-in form widgets.
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.. currentmodule:: django.forms
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A widget is Django's representation of a HTML input element. The widget
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handles the rendering of the HTML, and the extraction of data from a GET/POST
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dictionary that corresponds to the widget.
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Specifying widgets
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------------------
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Whenever you specify a field on a form, Django will use a default widget
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that is appropriate to the type of data that is to be displayed. To find
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which widget is used on which field, see the documentation about
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:ref:`built-in fields`.
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However, if you want to use a different widget for a field, you can
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just use the :attr:`~Field.widget` argument on the field definition. For
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example::
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from django import forms
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class CommentForm(forms.Form):
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name = forms.CharField()
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url = forms.URLField()
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comment = forms.CharField(widget=forms.Textarea)
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This would specify a form with a comment that uses a larger :class:`Textarea`
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widget, rather than the default :class:`TextInput` widget.
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Setting arguments for widgets
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-----------------------------
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Many widgets have optional extra arguments; they can be set when defining the
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widget on the field. In the following example, the
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:attr:`~SelectDateWidget.years` attribute is set for a
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:class:`~django.forms.extras.widgets.SelectDateWidget`::
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from django.forms.fields import DateField, ChoiceField, MultipleChoiceField
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from django.forms.widgets import RadioSelect, CheckboxSelectMultiple
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from django.forms.extras.widgets import SelectDateWidget
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BIRTH_YEAR_CHOICES = ('1980', '1981', '1982')
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FAVORITE_COLORS_CHOICES = (('blue', 'Blue'),
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('green', 'Green'),
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('black', 'Black'))
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class SimpleForm(forms.Form):
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birth_year = DateField(widget=SelectDateWidget(years=BIRTH_YEAR_CHOICES))
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favorite_colors = forms.MultipleChoiceField(required=False,
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widget=CheckboxSelectMultiple, choices=FAVORITE_COLORS_CHOICES)
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See the :ref:`built-in widgets` for more information about which widgets
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are available and which arguments they accept.
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Widgets inheriting from the Select widget
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-----------------------------------------
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Widgets inheriting from the :class:`Select` widget deal with choices. They
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present the user with a list of options to choose from. The different widgets
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present this choice differently; the :class:`Select` widget itself uses a
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``<select>`` HTML list representation, while :class:`RadioSelect` uses radio
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buttons.
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:class:`Select` widgets are used by default on :class:`ChoiceField` fields. The
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choices displayed on the widget are inherited from the :class:`ChoiceField` and
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changing :attr:`ChoiceField.choices` will update :attr:`Select.choices`. For
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example::
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>>> from django import forms
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>>> CHOICES = (('1', 'First',), ('2', 'Second',))
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>>> choice_field = forms.ChoiceField(widget=forms.RadioSelect, choices=CHOICES)
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>>> choice_field.choices
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[('1', 'First'), ('2', 'Second')]
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>>> choice_field.widget.choices
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[('1', 'First'), ('2', 'Second')]
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>>> choice_field.widget.choices = ()
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>>> choice_field.choices = (('1', 'First and only',),)
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>>> choice_field.widget.choices
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[('1', 'First and only')]
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Widgets which offer a :attr:`~Select.choices` attribute can however be used
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with fields which are not based on choice -- such as a :class:`CharField` --
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but it is recommended to use a :class:`ChoiceField`-based field when the
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choices are inherent to the model and not just the representational widget.
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Customizing widget instances
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----------------------------
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When Django renders a widget as HTML, it only renders the bare minimum
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HTML - Django doesn't add a class definition, or any other widget-specific
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attributes. This means that all :class:`TextInput` widgets will appear the same
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on your Web page.
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If you want to make one widget look different to another, you need to
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specify additional attributes for each widget. When you specify a
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widget, you can provide a list of attributes that will be added to the
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rendered HTML for the widget.
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For example, take the following simple form::
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from django import forms
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class CommentForm(forms.Form):
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name = forms.CharField()
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url = forms.URLField()
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comment = forms.CharField()
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This form will include three default :class:`TextInput` widgets, with default
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rendering -- no CSS class, no extra attributes. This means that the input boxes
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provided for each widget will be rendered exactly the same::
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>>> f = CommentForm(auto_id=False)
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>>> f.as_table()
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<tr><th>Name:</th><td><input type="text" name="name" /></td></tr>
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<tr><th>Url:</th><td><input type="text" name="url"/></td></tr>
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<tr><th>Comment:</th><td><input type="text" name="comment" /></td></tr>
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On a real Web page, you probably don't want every widget to look the same. You
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might want a larger input element for the comment, and you might want the
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'name' widget to have some special CSS class. To do this, you use the
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:attr:`Widget.attrs` argument when creating the widget:
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For example::
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class CommentForm(forms.Form):
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name = forms.CharField(
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widget=forms.TextInput(attrs={'class':'special'}))
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url = forms.URLField()
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comment = forms.CharField(
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widget=forms.TextInput(attrs={'size':'40'}))
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Django will then include the extra attributes in the rendered output:
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>>> f = CommentForm(auto_id=False)
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>>> f.as_table()
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<tr><th>Name:</th><td><input type="text" name="name" class="special"/></td></tr>
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<tr><th>Url:</th><td><input type="text" name="url"/></td></tr>
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<tr><th>Comment:</th><td><input type="text" name="comment" size="40"/></td></tr>
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.. _built-in widgets:
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Built-in widgets
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----------------
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Django provides a representation of all the basic HTML widgets, plus some
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commonly used groups of widgets:
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``Widget``
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~~~~~~~~~~
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.. class:: Widget
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This abstract class cannot be rendered, but provides the basic attribute :attr:`~Widget.attrs`.
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.. attribute:: Widget.attrs
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A dictionary containing HTML attributes to be set on the rendered widget.
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.. code-block:: python
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>>> name = forms.TextInput(attrs={'size': 10, 'title': 'Your name',})
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>>> name.render('name', 'A name')
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u'<input title="Your name" type="text" name="name" value="A name" size="10" />'
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``TextInput``
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~~~~~~~~~~~~~
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.. class:: TextInput
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Text input: ``<input type='text' ...>``
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``PasswordInput``
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~~~~~~~~~~~~~~~~~
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.. class:: PasswordInput
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Password input: ``<input type='password' ...>``
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Takes one optional argument:
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.. attribute:: PasswordInput.render_value
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Determines whether the widget will have a value filled in when the
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form is re-displayed after a validation error (default is ``False``).
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.. versionchanged:: 1.3
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The default value for
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:attr:`~PasswordInput.render_value` was
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changed from ``True`` to ``False``
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``HiddenInput``
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~~~~~~~~~~~~~~~
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.. class:: HiddenInput
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Hidden input: ``<input type='hidden' ...>``
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``MultipleHiddenInput``
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~~~~~~~~~~~~~~~~~~~~~~~
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.. class:: MultipleHiddenInput
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Multiple ``<input type='hidden' ...>`` widgets.
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A widget that handles multiple hidden widgets for fields that have a list
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of values.
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.. attribute:: MultipleHiddenInput.choices
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This attribute is optional when the field does not have a
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:attr:`~Field.choices` attribute. If it does, it will override anything
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you set here when the attribute is updated on the :class:`Field`.
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``FileInput``
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~~~~~~~~~~~~~
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.. class:: FileInput
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File upload input: ``<input type='file' ...>``
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``ClearableFileInput``
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~~~~~~~~~~~~~~~~~~~~~~
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.. class:: ClearableFileInput
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.. versionadded:: 1.3
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File upload input: ``<input type='file' ...>``, with an additional checkbox
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input to clear the field's value, if the field is not required and has
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initial data.
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``DateInput``
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~~~~~~~~~~~~~
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.. class:: DateInput
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Date input as a simple text box: ``<input type='text' ...>``
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Takes one optional argument:
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.. attribute:: DateInput.format
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The format in which this field's initial value will be displayed.
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If no ``format`` argument is provided, the default format is the first
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format found in :setting:`DATE_INPUT_FORMATS` and respects
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:ref:`format-localization`.
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``DateTimeInput``
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~~~~~~~~~~~~~~~~~
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.. class:: DateTimeInput
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Date/time input as a simple text box: ``<input type='text' ...>``
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Takes one optional argument:
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.. attribute:: DateTimeInput.format
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The format in which this field's initial value will be displayed.
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If no ``format`` argument is provided, the default format is the first
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format found in :setting:`DATETIME_INPUT_FORMATS` and respects
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:ref:`format-localization`.
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``TimeInput``
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~~~~~~~~~~~~~
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.. class:: TimeInput
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Time input as a simple text box: ``<input type='text' ...>``
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Takes one optional argument:
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.. attribute:: TimeInput.format
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The format in which this field's initial value will be displayed.
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If no ``format`` argument is provided, the default format is the first
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format found in :setting:`TIME_INPUT_FORMATS` and respects
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:ref:`format-localization`.
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``Textarea``
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~~~~~~~~~~~~
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.. class:: Textarea
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Text area: ``<textarea>...</textarea>``
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``CheckboxInput``
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~~~~~~~~~~~~~~~~~
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.. class:: CheckboxInput
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Checkbox: ``<input type='checkbox' ...>``
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Takes one optional argument:
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.. attribute:: CheckboxInput.check_test
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A callable that takes the value of the CheckBoxInput and returns
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``True`` if the checkbox should be checked for that value.
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``Select``
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~~~~~~~~~~
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.. class:: Select
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Select widget: ``<select><option ...>...</select>``
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.. attribute:: Select.choices
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This attribute is optional when the field does not have a
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:attr:`~Field.choices` attribute. If it does, it will override anything
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you set here when the attribute is updated on the :class:`Field`.
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``NullBooleanSelect``
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~~~~~~~~~~~~~~~~~~~~~
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.. class:: NullBooleanSelect
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Select widget with options 'Unknown', 'Yes' and 'No'
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``SelectMultiple``
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~~~~~~~~~~~~~~~~~~
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.. class:: SelectMultiple
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Similar to :class:`Select`, but allows multiple selection:
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``<select multiple='multiple'>...</select>``
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``RadioSelect``
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~~~~~~~~~~~~~~~
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.. class:: RadioSelect
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Similar to :class:`Select`, but rendered as a list of radio buttons within
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``<li>`` tags:
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.. code-block:: html
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<ul>
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<li><input type='radio' ...></li>
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...
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</ul>
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.. versionadded:: 1.4
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For more granular control over the generated markup, you can loop over the
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radio buttons in the template. Assuming a form ``myform`` with a field
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``beatles`` that uses a ``RadioSelect`` as its widget:
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.. code-block:: html+django
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{% for radio in myform.beatles %}
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<div class="myradio">
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{{ radio }}
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</div>
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{% endfor %}
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This would generate the following HTML:
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.. code-block:: html
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<div class="myradio">
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<label><input type="radio" name="beatles" value="john" /> John</label>
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</div>
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<div class="myradio">
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<label><input type="radio" name="beatles" value="paul" /> Paul</label>
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</div>
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<div class="myradio">
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<label><input type="radio" name="beatles" value="george" /> George</label>
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</div>
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<div class="myradio">
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<label><input type="radio" name="beatles" value="ringo" /> Ringo</label>
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</div>
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That included the ``<label>`` tags. To get more granular, you can use each
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radio button's ``tag`` and ``choice_label`` attributes. For example, this template...
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.. code-block:: html+django
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{% for radio in myform.beatles %}
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<label>
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{{ radio.choice_label }}
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<span class="radio">{{ radio.tag }}</span>
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</label>
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{% endfor %}
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...will result in the following HTML:
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.. code-block:: html
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<label>
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John
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<span class="radio"><input type="radio" name="beatles" value="john" /></span>
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</label>
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<label>
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Paul
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<span class="radio"><input type="radio" name="beatles" value="paul" /></span>
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</label>
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<label>
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George
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<span class="radio"><input type="radio" name="beatles" value="george" /></span>
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</label>
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<label>
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Ringo
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<span class="radio"><input type="radio" name="beatles" value="ringo" /></span>
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</label>
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If you decide not to loop over the radio buttons -- e.g., if your template simply includes
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``{{ myform.beatles }}`` -- they'll be output in a ``<ul>`` with ``<li>`` tags, as above.
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``CheckboxSelectMultiple``
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~~~~~~~~~~~~~~~~~~~~~~~~~~
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.. class:: CheckboxSelectMultiple
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Similar to :class:`SelectMultiple`, but rendered as a list of check
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buttons:
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.. code-block:: html
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<ul>
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<li><input type='checkbox' ...></li>
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...
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</ul>
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``MultiWidget``
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~~~~~~~~~~~~~~~
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.. class:: MultiWidget
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Wrapper around multiple other widgets. You'll probably want to use this
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class with :class:`MultiValueField`.
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Its ``render()`` method is different than other widgets', because it has to
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figure out how to split a single value for display in multiple widgets.
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Subclasses may implement ``format_output``, which takes the list of
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rendered widgets and returns a string of HTML that formats them any way
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you'd like.
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The ``value`` argument used when rendering can be one of two things:
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* A ``list``.
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* A single value (e.g., a string) that is the "compressed" representation
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of a ``list`` of values.
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In the second case -- i.e., if the value is *not* a list -- ``render()``
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will first decompress the value into a ``list`` before rendering it. It
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does so by calling the ``decompress()`` method, which
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:class:`MultiWidget`'s subclasses must implement. This method takes a
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single "compressed" value and returns a ``list``. An example of this is how
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:class:`SplitDateTimeWidget` turns a :class:`datetime` value into a list
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with date and time split into two seperate values::
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class SplitDateTimeWidget(MultiWidget):
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# ...
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def decompress(self, value):
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if value:
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return [value.date(), value.time().replace(microsecond=0)]
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return [None, None]
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When ``render()`` executes its HTML rendering, each value in the list is
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rendered with the corresponding widget -- the first value is rendered in
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the first widget, the second value is rendered in the second widget, etc.
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:class:`MultiWidget` has one required argument:
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.. attribute:: MultiWidget.widgets
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An iterable containing the widgets needed.
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``SplitDateTimeWidget``
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~~~~~~~~~~~~~~~~~~~~~~~
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.. class:: SplitDateTimeWidget
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Wrapper (using :class:`MultiWidget`) around two widgets: :class:`DateInput`
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for the date, and :class:`TimeInput` for the time.
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``SplitDateTimeWidget`` has two optional attributes:
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.. attribute:: SplitDateTimeWidget.date_format
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Similar to :attr:`DateInput.format`
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.. attribute:: SplitDateTimeWidget.time_format
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Similar to :attr:`TimeInput.format`
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``SplitHiddenDateTimeWidget``
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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.. class:: SplitHiddenDateTimeWidget
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Similar to :class:`SplitDateTimeWidget`, but uses :class:`HiddenInput` for
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both date and time.
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.. currentmodule:: django.forms.extras.widgets
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``SelectDateWidget``
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~~~~~~~~~~~~~~~~~~~~
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.. class:: SelectDateWidget
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Wrapper around three :class:`~django.forms.Select` widgets: one each for
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month, day, and year. Note that this widget lives in a separate file from
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the standard widgets.
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Takes one optional argument:
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.. attribute:: SelectDateWidget.years
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An optional list/tuple of years to use in the "year" select box.
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The default is a list containing the current year and the next 9 years.
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